With the increasing concern for safety, there is a need to provide safe materials for public and household use, including flame retardant transparent or translucent products for use by the consumer. As a result, many products are now required to meet certain flame retardant criteria byy local and federal governments as well as by the manufactures of such products. One set of conditions employed as a standard for measuring flame retardancy is set forth in Underwriters' Laboratories, Inc. Bulletin 94 pursuant to which materials are rated for flame retardant characteristics.
In the art, there are many known flame retardant additives which are employed by mixing them with the products to be rendered flame retardant. Such flame retardant additives have been known to be employed in amounts of about 5 to 20 weight percent in order to be effective to resist burning of those products with which they are employed. It has been found, however, that at these concentrations these flame retardant additives can have a degrading effect upon the products with which they are employed, thereby often resulting in the loss of valuable physical properties of the base product. This is particularly evident when known flame retardant additives are employed with polycarbonate resins, as many of these additives have a degrading effect upon the polymer.
In many instances, it is desirable that articles produced from fire retardant polycarbonate resins retain their transparent to translucent characteristics.